Glycogen synthase kinase-3β (GSK-3β) of grass carp (Ctenopharyngodon idella): Synteny, structure, tissue distribution and expression in oleic acid (OA)-induced adipocytes and hepatocytes

Glycogen synthase kinase-3β (GSK-3β) plays a crucial role in regulating lipid metabolism, endoplasmic reticulum (ER) stress and apoptosis in mammals, however, its gene structure and function is little known about in fish. Here, its two paralogs, grass carp (Ctenopharyngodon idella) GSK-3β1 and GSK-3β2 were isolated and characterized, encoding peptides of 421 and 457 amino acids, respectively. These two paralogs may have originated from the teleost-specific genome duplication (TSGD) event. Alignment of grass carp GSK-3β deduced amino acid sequences with select teleost species showed that the protein is conserved. However, two paralogs of the GSK-3β had great variation in gene structure: the GSK-3β1 contained eleven exons while the GSK-3β2 contained nine exons. The two paralogs were expressed in a wide range of tissues, GSK-3β1 was most expressed in adipose tissue, GSK-3β2 was most expressed in liver. In OA-induced adipocytes and hepatocytes, we found that GSK-3β1 mRNA expression was significantly increased only in adipocytes, while the mRNA expression of GSK-3β2 was dramatically increased both in adipocytes and hepatocytes. These results provide evidence that the GSK-3β may participate in the process of lipid accumulation in OA-induced adipocytes and hepatocytes of grass carp. [Display omitted] •GSK-3β1 and GSK-3β2 were cloned and characterized in grass carp.•These two isoforms could be originated from TSGD event.•The gene structure and functional domains of GSK-3β1 and GSK-3β2 were conserved.•Grass carp GSK-3β can respond to lipid accumulation in adipose tissue and liver.